The present invention relates to a feature provided by a navigation system whereby a route can be calculated that avoids at-grade railroad crossings.
Navigation systems are available that provide end users (such as drivers and passengers of the vehicles in which the navigation systems are installed) with various navigation-related functions and features. For example, some navigation systems are able to determine the fastest or shortest route to travel by roads between locations in a geographic region. Using input from the end user, and optionally from equipment that can determine one""s physical location (such as a GPS system), a navigation system can examine various potential routes between two locations to determine the fastest or shortest route to travel from a starting location to a destination location in a geographic region. The navigation system may then provide the end user with information about the route in the form of guidance that identifies the driving maneuvers required to be taken by the end user to travel from the starting location to the destination location. The guidance may take the form of visual and/or audio instructions that are provided along the way as the end user is traveling the route. Some navigation systems are able to show detailed maps on computer displays outlining routes to destinations, the types of maneuvers to be taken at various locations along the routes, locations of certain types of features, and so on.
In order to provide these and other navigating functions, navigation systems use geographic data. The geographic data may be in the form of one or more databases that include data that represent physical features in a geographic region. The geographic database may include data representing the roads and intersections in a geographic region and also may include information relating to the represented roads and intersections in the geographic region, such as turn restrictions at intersections, speed limits along the roads, street names of the various roads, address ranges along the roads, and so on.
Although navigation systems provide many useful features, there continues to be room for new features and improvements. One area in which there is room for improvement relates to providing routes that satisfy various needs or requirements of end users. As noted above, navigation systems are able to determine the fastest route between two locations. However, this determination relies upon certain assumptions. For example, determining the fastest route necessarily does not take into account unforeseen delays, such as accidents or weather conditions, that have not yet occurred. Another type of occurrence that can cause a delay is a railroad train crossing. Waiting for a train to cross can add many minutes of delay to a route. This delay can be inconvenient or expensive.
Accordingly, it would be advantageous if a route calculation function in a navigation system could account for possible delays at railroad crossings when calculating a route to a destination.
To address these and other objectives, embodiments of the present invention comprises a feature for a navigation system that provides information about railroad crossing locations. According to one aspect of the disclosed subject matter, a geographic database used by a navigation system includes data that indicate whether an at-grade railroad crossing is located along a road segment. Using this information, a route calculation function in the navigation system calculates a route to a destination that avoids road segments that have at-grade railroad crossings. In this way, the delays associated with waiting for a train to cross a road are avoided.
According to another aspect of the disclosed subject matter, a geographic database includes information that indicates an estimated amount of railroad traffic or a schedule of railroad traffic at an at-grade railroad crossing along a road segment. Then, using this additional information, the route calculation function in the navigation system is able to calculate a route to a destination that minimizes delays associated with at-grade railroad crossings.
For purposes of this disclosure, a xe2x80x9cnavigation systemxe2x80x9d is understood to mean a navigation system installed in a vehicle (i.e., an in-vehicle navigation system). A xe2x80x9cnavigation systemxe2x80x9d is also understood to mean any software application installed on a computer platform that provides navigation-related features and uses geographic data, including applications that are installed on personal computers, networks, portable electronic devices, and so on.